A339532 Numbers b > 1 such that the smallest three primes, i.e., 2, 3 and 5 are base-b Wieferich primes.

449, 557, 593, 649, 701, 757, 793, 901, 1349, 1457, 1493, 1549, 1601, 1657, 1693, 1801, 2249, 2357, 2393, 2449, 2501, 2557, 2593, 2701, 3149, 3257, 3293, 3349, 3401, 3457, 3493, 3601, 4049, 4157, 4193, 4249, 4301, 4357, 4393, 4501, 4949, 5057, 5093, 5149, 5201

Offset

1,1

Links

Table of n, a(n) for n=1..45.

Mathematica

Select[Range[2, 5250], Function[b, AllTrue[{2, 3, 5}, PowerMod[b, (# - 1), #^2] == 1 &]]] (* Michael De Vlieger, Dec 10 2020 *)

Prog

(PARI) is(n) = forprime(p=1, 5, if(Mod(n, p^2)^(p-1)!=1, return(0))); 1

Crossrefs

Cf. A256236. Row 1 of A319060.

Cf. smallest k primes are base-b Wieferich primes: A339531 (k=2), A339533 (k=4), A339534 (k=5), A339535 (k=6), A339536 (k=7), A339537 (k=8).

Sequence in context: A020466 A142420 A319060 * A105376 A325083 A243402

Adjacent sequences: A339529 A339530 A339531 * A339533 A339534 A339535

Keyword

nonn

Author

Felix Fröhlich, Dec 08 2020

Status

approved